Apparatus and method for simultaneously measuring bio signals

ABSTRACT

An apparatus and method for simultaneously measuring at least two different bio signals without interference are provided. The apparatus includes a stimulus signal generating unit generating the stimulus signal to be applied to a human body, a sensing unit contacting the human body, including a plurality of electrodes to which the stimulus signal is applied and from which at least one intermediate signal containing the first and second bio signals is detected, configured to share at least one of the plurality of electrodes to apply the stimulus signal or to detect each intermediate signal, and a signal acquisition unit separating and acquiring the first and second bio signals from each intermediate signal detected from the sensing unit.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This is a Divisional of application Ser. No. 11/090,051, now U.S. Pat.No. 7,758,513, filed on Mar. 28, 2005, which claims priority from KoreanPatent Application No. 10-2004-0021034, filed on Mar. 27, 2004 in theKorean Intellectual Property Office, and Korean Patent Application No.10-2005-0023489, filed on Mar. 22, 2005 in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein intheir entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Apparatuses and methods consistent with the present invention relate tobio signal measuring, and more particularly, to simultaneously measuringat least two different bio signals without interference.

2. Description of the Related Art

The health condition of a patient can be determined by measuring variousbio signals to detect abnormal health symptoms. Commonly, a patientvisits a doctor's office and the doctor utilizes medical instruments formeasuring bio signals precisely. Recently, to reduce the inconvenienceof visiting the doctor's office, research on remote medical treatmenthas been carried out. Various types of instruments for remotelymeasuring bio signals have been put on the market. However, if a patientis unskilled, the accuracy of the bio signal measurement is limited.Furthermore, since a plurality of measurement instruments should bepurchased to measure many kinds of bio signals, the costs that a patientshould pay are very high.

In a conventional bio signal measuring apparatus, sensors for sensingbio signals are connected in an octopus shape to a main body of theapparatus. A user connects by wire or wirelessly bio signal measurementmodules, such as a sphygmomanometer, a weight meter, and/or a SpO₂meter, to the main body of the apparatus. After this, items to bemeasured are selected from a key panel by the user. However, ameasurement item should be selected for every measurement, and ameasurement mode should be changed for each item. This is troublesome,and the time required for the measurement is increased. Furthermore,since the measurement modules should be connected to the main body, thesystem is complicated, and thus the costs for implementing the entiresystem are increased.

Other examples of conventional technologies for bio signal measurementare disclosed in U.S. Pat. No. 5,152,296 and Korean Patent PublicationNo. 2001-0096186. In U.S. Pat. No. 5,152,296, various sensors areintegrated into one sensor module for measuring more items, such aselectrocardiogram (ECG), SpO₂, and blood pressure signals. Thisarchitecture can increase the convenience of measurement in that variousbio signals can be measured in one measurement operation. However, sincesensors for each measurement item should be separately prepared, costsare still increased, and kinds of measurement items are limited due tospatial constraints of the sensor module. An integrated medicaldiagnosis apparatus disclosed in Korean Patent Publication No.2001-0096186 includes a sensor unit constituted by integrating aplurality of sensors for detecting bio signals of a patient and a moduleunit including changeable and pluggable medical instruments desired bythe patient by modularizing a plurality of medical instruments formeasuring information corresponding to the bio signals detected by thesensor unit. The apparatus further includes a rear case in which thesensor unit is formed with an external recess. By integrating thesensors for measuring bio signals and modularizing devices forcollecting the bio signals measured by the sensors, the user can easilymeasure his/her bio signals. However, in this case, since the biosignals to be measured are sequentially measured using a selectingswitch, the time required for measurement is longer, and it is difficultto simultaneously measure various bio signals at the same time.

Methods of measuring bio signals are largely divided into twocategories. First, bio signals naturally generated inside a human body,such as ECG, body temperature, respiration, and pulse, can be directlymeasured using electrodes. The ECG can be measured using a potentialdifference between two electrodes contacting the human body, e.g., twoelectrodes contacting a right end and a left end centering the heart.Second, bio signals, such as body fat, skin resistance, and the amountof blood flow, can be measured by applying a stimulus signal from theoutside and receiving a signal responding to the stimulus signal. Forexample, for the body fat, a stimulus signal is applied through theelectrodes contacting both ends, and signals detected from the sameelectrode or different electrodes are measured, and for the skinresistance, a stimulus signal is applied through an electrode contactingthe left end, and a signal detected from the same electrode contactingthe left end in response to the stimulus is measured. For signals thatcan be applied as the stimulus signal, light of a wavelength sensitivelyresponding to each bio signal or a constant alternative current of anoptimized frequency for each bio signal can be used. For example, thebody fat is optimized to a certain frequency of tens of kHz, and theskin resistance is optimized to a certain frequency between 20 Hz and 50Hz.

Interference between first and second bio signals does not occur in acase where measurement paths are different when two bio signals havingdifferent physical mechanisms are simultaneously measured, e.g., in acase where the first bio signal naturally generated is measured whilethe second bio signal is measured by irradiating light. However, in acase where the measurement paths are all the same, e.g., in a case wherethe first bio signal is measured while the second bio signal is measuredby applying a current, the measurement cannot be correctly achieved dueto the interference between the first and second bio signals.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method forsimultaneously measuring at least two different bio signals withoutinterference.

According to an aspect of the present invention, there is provided a biosignal measurement apparatus for simultaneously measuring a first biosignal generated in response to a stimulus signal and a second biosignal naturally generated, the apparatus comprising: a stimulus signalgenerating unit generating the stimulus signal to be applied to a humanbody; a sensing unit contacting the human body, including a plurality ofelectrodes to which the stimulus signal is applied and from which atleast one intermediate signal containing the first and second biosignals is detected, configured to share at least one of the pluralityof electrodes to apply the stimulus signal or to detect eachintermediate signal; and a signal acquisition unit separating andacquiring the first and second bio signals from each intermediate signaldetected from the sensing unit.

According to another aspect of the present invention, there is provideda bio signal measurement method of simultaneously measuring a first biosignal generated in response to a stimulus signal and a second biosignal naturally generated, the method comprising: providing a sensingunit contacting a human body, including a plurality of electrodes towhich the stimulus signal is applied and from which at least oneintermediate signal containing the first and second bio signals isdetected, configured to share at least one of the plurality ofelectrodes to apply the stimulus signal or to detect each intermediatesignal; generating the stimulus signal to be applied to the human body;and separating and acquiring the first and second bio signals from eachintermediate signal detected from the sensing unit.

According to still another aspect of the present invention, there isprovided a computer-readable recording medium having recorded thereon acomputer-readable program for performing the above method.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a schematic block diagram of a bio signal measurementapparatus according to a first exemplary embodiment of the presentinvention;

FIG. 2 is an exemplary detailed block diagram of the bio signalmeasurement apparatus shown in FIG. 1;

FIG. 3 is another exemplary detailed block diagram of the bio signalmeasurement apparatus shown in FIG. 1;

FIGS. 4A and 4B show examples of a temporal separating method adopted ina first and a second temporal separating units shown in FIGS. 1 through3;

FIG. 5 is an example of combining two alternate currents in a combiningunit shown in FIG. 3;

FIG. 6 is a schematic block diagram of a bio signal measurementapparatus according to a second exemplary embodiment of the presentinvention;

FIG. 7 is a schematic block diagram of a bio signal measurementapparatus according to a third exemplary embodiment of the presentinvention;

FIG. 8 is a schematic block diagram of a bio signal measurementapparatus according to a fourth exemplary embodiment of the presentinvention; and

FIG. 9 is a flowchart of a bio signal measurement method according to afifth exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

Hereinafter, exemplary embodiments of the present invention will now bedescribed in detail with reference to the accompanying drawings.

First, a bio signal generated in response to a stimulus signal is calleda first bio signal, and a bio signal naturally generated is called asecond bio signal. In the present invention, a sensing unit (130 ofFIG. 1) contacting a human body comprises a plurality of electrodes towhich the stimulus signal is applied and from which an intermediatesignal containing the first and second bio signals is detected.Particularly, the sensing unit is configured to share at least one ofthe plurality of electrodes to detect each intermediate signal. Inaddition, a signal acquisition unit (160 of FIG. 1) separates andacquires the first and second bio signals from each intermediate signaldetected from the sensing unit, by using at least one of a temporalseparation and an electric separation. The temporal separation may beused irrespective of frequency bands in which each of the first andsecond bio signal to be simultaneously measured exists, since signalsare temporally separated. However, the performance of the temporalseparation is closely related to the processing speed of a controller(110 of FIG. 1). Therefore, if items to be simultaneously measuredincrease and a low-level controller is used, it is difficult toguarantee the performance. The electric separation may separate signalsby means of a combination of a filtering unit and an isolating unit, forobtaining signals of a desired frequency band from an intermediatesignal detected from the sensing unit. However, the electric separationcan be used just when frequency bands in which each of the first andsecond bio signal to be simultaneously measured exists are separatedfrom each other.

FIG. 1 is a schematic block diagram of a bio signal measurementapparatus according to a first exemplary embodiment of the presentinvention, which measures the first and second bio signals using thetemporal separation. The apparatus includes an item selection unit 100,a controller 110, a stimulus signal generating unit 120, a firsttemporal separating unit 130, a sensing unit 140, a second temporalseparating unit 150, a signal acquisition unit 160, a signal analyzingunit 170, a storage unit 180, and a display unit 190. The item selectionunit 100 may be optionally included.

Referring to FIG. 1, the item selection unit 100 selects bio signals,which a user desires to simultaneously measure. The user can select atleast one of various first bio signals and at least one of varioussecond bio signals. In another exemplary embodiment, the item selectionunit 100 selects at least one bio signal, which a user desires not tosimultaneously measure, among a plurality of items set in advance.

The controller 110 generates a control signal to switch a first and asecond temporal separating units 130 and 150 in a constant time intervalfor preventing the interference between the first and second bio signalsto be simultaneously measured. For example, the controller 110 dividesan entire time T required for simultaneously measuring the first andsecond bio signals into very short sampling periods of a pulse signal,as shown in FIGS. 4A and 4B. In FIGS. 4A and 4B, a first interval (Ta)is used to apply the stimulus signal to the sensing unit (140) and tomeasure the first bio signal and a second interval (Tb) is used tomeasure the second bio signal.

The stimulus signal generating unit 120 generates a stimulus signal bestresponding to a human body to be applied to the first temporalseparating unit 130, with regard to each first bio signal. For example,if the first bio signal is a body fat signal, an alternate current (AC)having a certain frequency of tens of kHz is used as the stimulussignal, and if the first bio signal is a skin resistance signal, an ACoptimized to a certain frequency between 20 Hz and 50 Hz is used as thestimulus signal. Also, the stimulus signal generating unit 120 storesstimulus signals mapped to each of the first bio signals. Accordingly,if a user selects items to be simultaneously measured, correspondingstimulus signals are applied to the first temporal separating unit 130.If two or more first bio signals are selected, stimulus signalscorresponding to each of first bio signals are generated and thestimulus signals are combined to then be applied to the first temporalseparating unit 130.

The first temporal separating unit 130 operates in response to thecontrol signal provided from the controller 110 and preventsinterference caused by the stimulus signal during the measurement of thesecond bio signal. According to this, the stimulus signal is applied tothe sensing unit 140 in a constant time interval.

The sensing unit 140 includes a plurality of electrodes attachable to ahuman body, to which the stimulus signal is applied and from which atleast one intermediate signal containing the first and second biosignals is detected. The sensing unit 140 is configured to share atleast one of the plurality of electrodes to apply the stimulus signal orto detect each intermediate signal. In an exemplary embodiment, thesensing unit 140 includes four electrodes, i.e., two electrodes for eachof the left and right palms. In another exemplary embodiment, thesensing unit 140 includes two electrodes, i.e., one electrode for eachof the left and right palms. Any region other than the left and rightpalms may be used if the first or the second bio signal can be detectedin the region. With regard to the first bio signals, the stimulus signalis applied to at least two of the plurality of electrodes and anintermediate signal detected from at least two of the plurality ofelectrodes is used to measure the first bio signals. With regard to thesecond bio signals, an intermediate signal detected from at least two ofthe plurality of electrodes is used to measure the second bio signals.

The second temporal separating unit 150 operates in response to thecontrol signal provided from the controller 110 and preventsinterference caused by the first or second bio signal during obtainingthe first and second bio signals in the signal acquisition unit 160.According to this, each of a first intermediate signal and a secondintermediate signal is detected from the plurality of electrodesincluded in the sensing unit 140 in a constant time interval. The secondtemporal separating unit 150 operates in synchronization with the firsttemporal separating unit 130 and both may be implemented using an analogswitch.

The signal acquisition unit 160 operates depending on the control signalprovided from the controller 110, and separates and acquires the firstand second bio signals from the first and second intermediate signalsdetected from the sensing unit 140 in a constant time interval dependingon the operation of the second temporal separating unit 150. If thereare a plurality of the first bio signals to be simultaneously measuredand stimulus signal having a frequency corresponding to each first biosignal are applied to the sensing unit 140, a corresponding first biosignal can be obtained using each frequency.

The signal analyzing unit 170 analyzes the first and second bio signalsacquired by the signal acquisition unit 160 and obtains correspondingdata. For example, data corresponding to the first bio signal such asthe body fat or the skin resistance is measured using impedance obtainedfrom voltage difference between two electrodes and the second bio signalsuch as the ECG can be obtained from potential difference obtained usingat least two electrodes.

The data corresponding to the first and second bio signals obtained asthe analysis results of the signal analyzing unit 170 is stored in thestorage unit 180 or displayed on the display unit 190.

FIG. 2 is an exemplary detailed block diagram of the bio signalmeasurement apparatus shown in FIG. 1.

In the bio signal measurement apparatus shown in FIG. 2, one measurementitem of the second bio signals is selected or measured. Referring toFIG. 2, a stimulus signal generating unit 220 includes a first currentgenerator 221, and a first temporal separating unit 230 includes a firstswitch 231. A sensing unit 240 includes a first electrode group 241including first and third electrodes E1 and E3 and a second electrodegroup 242 including second and fourth electrodes E2 and E4. A secondtemporal separating unit 250 includes a second switch 251 and a thirdswitch 253. A signal acquisition unit 260 includes a first acquisitionunit 261 and a second acquisition unit 264. The first acquisition unit261 includes a first amplifier 262 and a first filtering unit 263, andthe second acquisition unit 264 includes a second amplifier 265 and asecond filtering unit 266.

For the convenience of description, a body fat signal or a skinresistance signal is an example of the first bio signals generated inresponse to an applied current and an ECG signal is used as an exampleof the naturally generated second bio signals.

The ECG signal is generated by an electrical activity of the heart anddetected using potential difference(s) detected from at least twopositions apart from the heart. The potential differences vary accordingto distances from the heart. Thus, in the present exemplary embodiment,the palms are used as an example of the measurement positions. In orderto measure the ECG, in the sensing unit 240, three electrodes e.g., thesecond through fourth electrodes E2, E3 and E4 or two electrodes e.g.,the third and fourth electrodes E3 and E4. The body fat is measuredusing resistance values detected from both ends of the human bodyaccording to the amount of body fat. That is, a constant AC is appliedand then a potential difference between two electrodes is converted to aresistance value. Here, for a frequency of the AC, a frequency whichresponds well to the body fat component in the human body, e.g., 50 kHz,is used. When two electrodes are used for measuring the body fat, the ACis applied to the first and second electrodes E1 and E2, and then an ACvoltage between the first and second electrodes E1 and E2 is measured.When four electrodes are used for measuring the body fat, the AC isapplied to the first and second electrodes E1 and E2, and then an ACvoltage between the third and fourth electrodes E3 and E4 is measured.The measured AC voltage is converted to impedance. In the presentexemplary embodiment, four electrodes are used. If sweat comes out fromthe skin in accordance with a change in the autonomic nervous system, aresistance value of the surface of the skin varies. For a frequency ofthe AC, a frequency well responding to the skin resistance, e.g., acertain frequency between 20 Hz and 50 Hz, is used. In order to measurethe skin resistance, the AC is applied to the first and third electrodesE1 and E3, and then an AC voltage between the first and third electrodesE1 and E3 is measured. The measured AC voltage is converted to aresistance value.

An operation of the present exemplary embodiment will now be describedbased on the bio signal measurement principle.

Referring to FIG. 2, the first current generator 221 generates an AChaving a frequency corresponding to each of the first bio signals. Thatis, the first current generator 221 generates the AC (I_(f2) of FIG. 5)having the frequency of 50 kHz if the body fat is the second bio signal.

The first switch 231 performs a switching operation depending on thecontrol signal from the controller 110. The first switch 231 connects acontact point a1 to a contact point b1 in a Ta period (refer to FIGS. 4Aand 4B) for measuring a first bio signal. In a Tb period (refer to FIGS.4A and 4B) for measuring a second bio signal, the first switch 231connects the contact point a1 to a contact point c1. Accordingly, the ACprovided by the first current generator 221 is not applied to the secondelectrode E2 of the sensing unit 240 in the Tb period, and the ACprovided by the first current generator 221 is applied to the secondelectrode E2 of the sensing unit 240 in the Ta period. Even if the ACprovided by the first current generator 221 is always applied to thefirst electrode E1 of the sensing unit 240 regardless to periods, sincethe AC is not applied to the second electrode E2 of the sensing unit 240in the Tb period, a current loop is not formed. Thus no interferenceoccurs when the second bio signal is measured in the Tb period.

The second and third switches 251 and 253 performs a switching operationin synchronization with the first switch 231 depending on the controlsignal from the controller 110. In the Ta period (refer to FIGS. 4A and4B) for measuring a first bio signal, a contact point a2 of the secondswitch 251 is connected to a contact point b2, and a contact point a3 ofthe third switch 253 is connected to a contact point b3. In the Tbperiod (refer to FIGS. 4A and 4B) for measuring a second bio signal, thecontact point a2 of the second switch 251 is connected to a contactpoint c2, and the contact point a3 of the third switch 253 is connectedto a contact point c3. Accordingly, voltages detected from the third andfourth electrodes E3 and E4 of the sensing unit 240 if the first biosignal is the body fat are provided to the first acquisition unit 261included in the signal acquisition unit 260 in the Ta period. Inaddition, voltages detected from the third and fourth electrodes E3 andE4 of the sensing unit 240 are provided to the second acquisition unit264 included in the signal acquisition unit 260 in the Tb period.

In the first acquisition unit 261, the first amplifier 262 amplifies theAC voltage between the third and fourth electrodes E3 and E4 connectedthrough the second and third switches 251 and 253 in every Ta period andprovides the amplified AC voltage to the first filtering unit 263. Thefirst filtering unit 263 cancels noise components by filtering theamplified AC voltage provided from the first amplifier 262 and providesthe noise-cancelled AC voltage to the signal analyzing unit (170 of FIG.1). In the second acquisition unit 264, the second amplifier 265 setsthe second electrode E2 connected through the first switch 231 in everyTb period as a right leg driver of the ECG, differentially amplifies adifference, i.e., a potential difference signal, between the voltages ofthe third and fourth electrodes E3 and E4 connected through the secondand third switches 251 and 253, and provides the differentiallyamplified potential difference signal to the second filtering unit 266.The second filtering unit 266 cancels noise components by filtering theamplified potential difference signal provided from the second amplifier265 and provides the noise-cancelled potential difference signal to thesignal analyzing unit (170 of FIG. 1).

In a case that there is a demand of measuring the skin resistanceinstead of the body fat, it may be easily implemented by modifying theconnection relation between the sensing unit 240 and the signalacquisition unit 260.

FIG. 3 is another exemplary detailed block diagram of the bio signalmeasurement apparatus shown in FIG. 1.

Referring to FIG. 3, a stimulus signal generating unit 320 includes afirst and a second current generator 321 and 323 and a combining unit325, and a signal acquisition unit 360 includes a first acquisition unit361, a second acquisition unit 365, and a third acquisition unit 369.The first acquisition unit 361 includes a first amplifier 362, a firstseparating unit 363 and a first filtering unit 364, the secondacquisition unit 365 includes a second amplifier 366, a secondseparating unit 367 and a second filtering unit 368, and the thirdacquisition unit 369 includes a third amplifier 370 and a thirdfiltering unit 371. The detailed description of the parts which are thesame as those in the apparatus shown in FIG. 2 will be omitted and thedifferent parts will be mainly described.

Referring to FIG. 3, the first and second current generators 321 and 323generate ACs having a frequency corresponding to each of the two firstbio signals. For example, the first current generator 321 generates afirst AC (I_(f1) of FIG. 5) having a first frequency f1 between 20 Hzand 50 Hz for measuring the skin resistance and the second currentgenerator 323 generates a second AC (I_(f2) of FIG. 5) having a secondfrequency f2 of 50 kHz for measuring the body fat. The combining unit325 generates a combined AC (I_(m) of FIG. 5) by combining the first andsecond ACs I_(f1) and I_(f2) generated by the first and second currentgenerators 321 and 323 and provides the combined AC to the firsttemporal separating unit 330. If one first bio signal other than theskin resistance and the body fat is additionally measured, a third AC isgenerated to then be combined with the first and second ACs and thecombined AC to the first temporal separating unit 330.

In the first acquisition unit 361, the first amplifier 362 amplifies theAC voltage between the third and fourth electrodes E3 and E4 connectedthrough the second and third switches 351 and 353 in every Ta period andprovides the amplified AC voltage to the first separating unit 363. Thefirst separating unit 363 separates a portion corresponding to the firstfrequency component f1 from the amplified AC voltage. The firstfiltering unit 364 cancels noise components by filtering the AC voltagehaving the first frequency component f1 separated from the firstseparating unit 363 and provides the noise-cancelled AC voltage to thesignal analyzing unit (170 of FIG. 1).

In the second acquisition unit 365, the second amplifier 366 amplifiesthe AC voltage between the third and fourth electrodes E3 and E4connected through the second and third switches 351 and 353 in every Taperiod and provides the amplified AC voltage to the second separatingunit 367. The second separating unit 367 separates a portioncorresponding to the second frequency component f2 from the amplified ACvoltage. The second filtering unit 368 cancels noise components byfiltering the AC voltage having the second frequency component f2separated from the second separating unit 367 and provides thenoise-cancelled AC voltage to the signal analyzing unit (170 of FIG. 1).

In the third acquisition unit 369, the third amplifier 370 sets thesecond electrode E2 connected through the first switch 231 in every Tbperiod as a right leg driver of the ECG, differentially amplifies adifference, i.e., a potential difference signal, between the voltages ofthe third and fourth electrodes E3 and E4 connected through the secondand third switches 251 and 253, and provides the differentiallyamplified potential difference signal to the third filtering unit 371.The third filtering unit 371 cancels noise components by filtering theamplified potential difference signal provided from the third amplifier370 and provides the noise-cancelled potential difference signal to thesignal analyzing unit (170 of FIG. 1).

Here, if the number of the first bio signals to be simultaneouslymeasured is m (m is an integer equal to or greater than 2) and the totalof bio signals to be simultaneously measured including the second biosignal is n, apparatuses shown in FIGS. 2 and 3 may be modified asfollows.

First, for the apparatus of FIG. 2, a switching operation of the firstand second temporal separating units 230 and 250 is performed n timeswithin one sampling period T1 and one bio signal is measured in each ofswitching operations.

Second, for the apparatus of FIG. 3, the combining unit 325 combines ACshaving m frequencies to then be applied to the sensing unit 340 and mseparating units are arranged to separate an AC voltage having eachfrequency component from the AC voltage detected from the sensing unit340. According to this, a switching operation of the first and secondtemporal separating units 230 and 250 is performed twice within onesampling period T1 and the first or second bio signal is measured ineach of switching operations. It is required that a frequency band inwhich each of m first bio signals exists is separated from each other.

FIGS. 4A and 4B show examples of a temporal separating method adopted inthe first temporal separating units 130, 230 and 330 and the secondtemporal separating units 150, 250 and 350 shown in FIGS. 1 through 3.Here, a switching operation is performed twice within one samplingperiod T1. Referring to FIGS. 4A and 4B, the first bio signal ismeasured in the Ta period and the second bio signal is measured in theTb period. In particular, a Td period shown in FIG. 4B is used fordischarging the stimulus signal applied to the human body in the Taperiod and arranged between the Ta period and the Tb period. The size ofthe Td period may be empirically obtained through experiments orcomputer simulations. According to this, after the first bio signal hasbeen measured, the remaining stimulus signal in the human body can bedischarged, which results in minimizing interference caused by thestimulus signal during the measurement of the second bio signal. Formore effective discharging, a resistor (not shown) and a switch (notshown) connected in series are arranged between the second electrode(E2) of the sensing units 240 and 340 to which the stimulus signal isapplied and the ground and the switch is turned on in the Td period. Asa result, in the Td period, prompt discharging may be achieved via theresistor. In the present exemplary embodiments, the sampling period is500 Hz, i.e., 2 ms, but is not limited thereto.

FIG. 6 is a schematic block diagram of a bio signal measurementapparatus according to a second exemplary embodiment of the presentinvention, which measures the first and second bio signals using theelectric separation. The apparatus includes an item selection unit 600,a stimulus signal generating unit 620, a sensing unit 640, a signalacquisition unit 660 and a signal analyzing unit 670. The item selectionunit 600 may be optionally included. The signal acquisition unit 660comprises first and second acquisition units. The first acquisition unitincludes a first filtering unit 661, a first amplifier 662 and a secondfiltering unit 663 and the second acquisition unit includes a thirdfiltering unit 664, an isolating unit 665, a second amplifier 666 and afourth filtering unit 667. The apparatus of FIG. 6 adopts a differentsignal acquisition unit 660 instead of the first and second temporalseparating units 130 and 150, comparing with the apparatus of FIG. 1.The detailed description of the parts which are the same as those in theapparatus shown in FIG. 1 will be omitted and the different parts willbe mainly described. Here, the body fat is used as the first bio signaland the ECG is used as the second bio signal.

Referring to FIG. 6, a stimulus signal for measuring the first biosignal is applied to the first and second electrodes E1 and E2 of thesensing unit 640. When the second electrode sets as a right leg driver(G) of the ECG, voltages detected from the third and fourth electrodesE3 and E4 are provided to both the first filtering unit 661 and thethird filtering unit 664.

In the signal acquisition unit 660, the first filtering unit 661 filtersa frequency band in which the first bio signal exists from the detectedvoltages, i.e., an intermediate signal provided from the sensing unit640. The first amplifier 662 amplifies the intermediate signal providedfrom the first filtering unit 661. The second filtering unit 663 removesnoise components from the intermediate signal provided from the firstamplifier 662 to be provided as the first bio signal.

The third filtering unit 664 filters a frequency band in which thesecond bio signal exists from the detected voltages, i.e., theintermediate signal provided from the sensing unit 640. The isolatingunit 665 isolates the stimulus signal contained in the intermediatesignal provided from the third filtering unit 664. The isolating unit665 comprises any one selected from a group of a buffer, a photo couplerand a transformer. The second amplifier 666 amplifies the intermediatesignal provided from the isolating unit 665. The fourth filtering unit667 removes noise components from the intermediate signal provided fromthe second amplifier 666 to be provided as the second bio signal.

In order to effectively measure the first and second bio signals usingthe apparatus of FIG. 6, it may be preferable that each frequency bandin which the first or the second bio signal exists is separated fromeach other.

FIG. 7 is a schematic block diagram of a bio signal measurementapparatus according to a third exemplary embodiment of the presentinvention, which measures the first and second bio signals using boththe temporal separation and the electric separation. The apparatusincludes an item selection unit 700, a controller 710, a stimulus signalgenerating unit 720, a first temporal separating unit 730, a sensingunit 740, a second temporal separating unit 750, a signal acquisitionunit 760 and a signal analyzing unit 770. The item selection unit 700may be optionally included. The stimulus signal generating unit 720comprises first and second current generators 721 and 723. The signalacquisition unit 760 includes first through third acquisition units. Thefirst acquisition unit comprises a first amplifier 761 and a firstfiltering unit 762. The second acquisition unit comprises a secondfiltering unit 763, an isolating unit 764, a second amplifier 765 and athird filtering unit 766. The third acquisition unit comprises a fourthfiltering unit 767, a third amplifier 768 and a fifth filtering unit769. The apparatus of FIG. 7 additionally adopts the first and secondtemporal separating units 730 and 750, comparing with the apparatus ofFIG. 6. The detailed description of the parts which are the same asthose in the apparatus shown in FIG. 6 will be omitted and the differentparts will be mainly described. Here, the body fat is used as the firstbio signal and the ECG is used as the second bio signal.

Referring to FIG. 7, the sensing unit 740 comprises a first electrode E1for applying the first and second stimulus signals and detecting thefirst intermediate signal, a second electrode E2 for applying the secondstimulus signal and used as a right leg driver, a third electrode E3 forapplying the first stimulus signal and detecting the first and secondintermediate signals, and a fourth electrode E4 for detecting the firstand second intermediate signals.

The first temporal separating unit 730 operates in response to thecontrol signal provided from the controller 710 and applies a firststimulus signal in a first interval, i.e., the period of each samplingperiod and a second stimulus signal in a second interval, i.e., the Tbperiod of each sampling period, to the human body via the sensing unit740. The first stimulus signal is used for measuring the skin resistanceand the second stimulus signal is used for measuring the body fat.

The second temporal separating unit 750 operates in response to thecontrol signal and provides a first intermediate signal detected fromthe first and third electrodes E1 and E3 of the sensing unit 740 in theTa period and a second intermediate signal detected from the third andfourth electrodes E3 and E4 of the sensing unit 740 in the Tb period, tothe signal acquisition unit 760.

The signal acquisition unit 760 obtains the first bio signal, i.e., theskin resistance signal from the first intermediate signal using thetemporal separation and the first bio signal, i.e., the body fat signaland the second bio signal, i.e., the ECG signal from the secondintermediate signal using the filtering and electric separation.

In the signal acquisition unit 760, the first amplifier 761 amplifiesthe first intermediate signal, i.e., voltages detected from the firstand third electrodes E1 and E3 of the sensing unit 740 in the Ta period.The first filtering unit 762 removes noise components from the firstintermediate signal provided from the first amplifier 761 to be providedas the first bio signal, i.e., the skin resistance signal.

The second filtering unit 763 filters a frequency band in which thesecond bio signal, i.e., the ECG signal exists from the secondintermediate signal, i.e., voltages detected from the third and fourthelectrodes E3 and E4 of the sensing unit 740 in the Tb period. Theisolating unit 764 isolates the second stimulus signal contained in thesecond intermediate signal provided from the second filtering unit 763.The isolating unit 764 comprises any one selected from a group of abuffer having a high input impedance, a photo coupler and a transformer.The second amplifier 765 amplifies the second intermediate signalprovided from the isolating unit 764. The third filtering unit 766removes noise components from the second intermediate signal providedfrom the second amplifier 765 to be provided as the second bio signal,i.e., the ECG signal.

The fourth filtering unit 767 filters a frequency band in which thefirst bio signal, i.e., the body fat signal exists from the secondintermediate signal, i.e., voltages detected from the third and fourthelectrodes E3 and E4 of the sensing unit 740 in the Tb period. The thirdamplifier 768 amplifies the second intermediate signal provided from thefourth filtering unit 767. The fifth filtering unit 769 removes noisecomponents from the second intermediate signal provided from the thirdamplifier 768 to be provided as the first bio signal, i.e., the body fatsignal.

In the apparatus of FIG. 7, the skin resistance signal whose frequencyband is adjacent to that of the ECG signal is separated using the firstand second temporal separating unit 730 and 750. Also, the body fatsignal and the ECG signal whose frequency bands are separated from eachother, obtained through the temporal separation are separated from eachother using the second and fourth filtering unit 763 and 767 and theisolating unit 764. As a result, a variety of bio signals can beaccurately measured regardless of their frequency bands. In addition, acircuit for removing a jitter may be arranged next to the secondtemporal separating unit 750. In addition, a circuit for matchingimpedance may be arranged to compensate for a reduction of impedancecaused by the jitter removing circuit.

FIG. 8 is a schematic block diagram of a bio signal measurementapparatus according to a fourth exemplary embodiment of the presentinvention, which measures the first and second bio signals using boththe temporal separation and the electric separation. The apparatusincludes an item selection unit 800, a controller 810, a stimulus signalgenerating unit 820, a first temporal separating unit 830, a sensingunit 840, a second temporal separating unit 850, a signal acquisitionunit 860 and a signal analyzing unit 870. The item selection unit 800may be optionally included. The stimulus signal generating unit 820comprises first and second current generators 821 and 823. The signalacquisition unit 860 includes first through third acquisition units. Thefirst acquisition unit comprises a first amplifier 861 and a firstfiltering unit 862. The second acquisition unit comprises a secondfiltering unit 863, an isolating unit 864, a second amplifier 865 and athird filtering unit 866. The third acquisition unit comprises a fourthfiltering unit 867, a third amplifier 868 and a fifth filtering unit869. The apparatus of FIG. 8 additionally adopts the first and secondtemporal separating units 830 and 850 and their locations, comparingwith the apparatus of FIGS. 6 and 7. The detailed description of theparts which are the same as those in the apparatus shown in FIGS. 6 and7 will be omitted and the different parts will be mainly described.Here, the body fat is represented by the first bio signal and the ECG isrepresented by the second bio signal.

Referring to FIG. 8, the sensing unit 840 comprises a first electrode E1for applying the first and second stimulus signals and detecting thefirst intermediate signal, a second electrode E2 for applying the secondstimulus signal and used as a right leg driver, a third electrode E3 forapplying the first stimulus signal and detecting the first and secondintermediate signals, and a fourth electrode E4 for detecting the firstand second intermediate signals.

The first temporal separating unit 830 operates in response to thecontrol signal provided from the controller 810 and applies a firststimulus signal to the human body via the sensing unit 840 in a firstinterval, i.e., the Ta period of each sampling period. The firststimulus signal is used for measuring the skin resistance.

The second temporal separating unit 850 operates in response to thecontrol signal and provides a first intermediate signal detected fromthe third and fourth electrodes E3 and E4 of the sensing unit 840 in theTa period and a second intermediate signal detected from the third andfourth electrodes E3 and E4 of the sensing unit 840 in the Tb period ofthe sampling period to the signal acquisition unit 860.

Here, a second stimulus signal used for measuring the body fat isapplied to the human body via the sensing unit 840 regardless ofperiods. The third intermediate signal is detected from the third andfourth electrodes E3 and E4 of the sensing unit 840 regardless ofperiods.

The signal acquisition unit 860 obtains the body fat signal using thefiltering and the skin resistance and the ECG signal using the temporalseparation and the skin resistance signal.

In the signal acquisition unit 860, the first amplifier 861 amplifiesthe first intermediate signal, i.e., voltages detected from the firstand third electrodes E1 and E3 of the sensing unit 840 in the Ta period.The first filtering unit 862 removes noise components from the firstintermediate signal provided from the first amplifier 861 to be providedas the first bio signal, i.e., the skin resistance signal.

The second filtering unit 863 filters a frequency band in which thesecond bio signal, i.e., the ECG signal, exists from the secondintermediate signal, i.e., voltages detected from the third and fourthelectrodes E3 and E4 of the sensing unit 840 in the Tb period. Theisolating unit 864 isolates the second stimulus signal contained in thesecond intermediate signal provided from the second filtering unit 863.The isolating unit 864 comprises any one selected from a group of abuffer having a high input impedance, a photo coupler and a transformer.The second amplifier 865 amplifies the second intermediate signalprovided from the isolating unit 864. The third filtering unit 866removes noise components from the second intermediate signal providedfrom the second amplifier 865 to be provided as the second bio signal,i.e., the ECG signal.

The fourth filtering unit 867 filters a frequency band in which thefirst bio signal, i.e., the body fat signal exists from the thirdintermediate signal, i.e., voltages detected from the third and fourthelectrodes E3 and E4 of the sensing unit 740 regardless of periods. Thethird amplifier 868 amplifies the third intermediate signal providedfrom the fourth filtering unit 867. The fifth filtering unit 869 removesnoise components from the second intermediate signal provided from thethird amplifier 868 to be provided as the first bio signal, i.e., thebody fat signal.

A component (not shown) for measuring third bio signals such as bloodsugar by irradiating light of a specific wavelength as an externalstimulus can be added to the bio signal measurement apparatusesaccording to the present invention.

For the bio signal measurement apparatuses according to the exemplaryembodiments, the item selection unit 100 and the controller 110 can besubstituted by a signal stimulus signal generating unit 120 generatingpredetermined ACs of a different specific frequency and the first andsecond switching units 130 and 150 can be automatically switched everypredetermined time in a rotary motor shape. In this case, it may bepreferable that the signal analyzing unit 170 analyzes signals providedby the signal acquisition unit 160 after a stabilizing duration for apredetermined time.

In the bio signal measurement apparatuses according to the exemplaryembodiments, the stimulus signal for the first bio signals are notdefinitely limited to the AC. For example, any one of AC and directcurrent (DC) can be used for measuring the skin resistance. Therefore,when two first bio signals, such as the body fat signal and the skinresistance signal are measured at the same time, without the combiningunit 323, an AC having a specific frequency for measuring the body fatand a DC for measuring the skin resistance are applied to the sensingunit 340, and thus an AC voltage having the specific frequency and a DCvoltage can be separated from a signal sensed by the sensing unit 340 asthe first bio signal for the body fat and the first bio signal for theskin resistance.

FIG. 9 is a flowchart of a bio signal measurement method according tostill a fifth exemplary embodiment of the present invention.

Referring to FIG. 9, in operation 910, when a user attaches the sensingunit 140 included in the measurement apparatus to a specific region of ahuman body, a stimulus signal, e.g., an AC of a predetermined frequency,is applied to the sensing unit 140. Methods of applying the stimulussignal can be largely divided into five categories. First, in a casewhere one kind of the first bio signals and one kind of the second biosignals are measured, an AC of a predetermined frequency is applied inevery Ta of a sampling period, as shown in FIG. 2. Second, in a casewhere one kind of the first bio signals and at least two kinds of thesecond bio signals are measured, at least two ACs having a differentfrequency are combined, and the combined ACs are applied in every Taperiod of a sampling period, as shown in FIG. 3. Third, an AC of apredetermined frequency is consistently applied irrespective of the Taand Tb periods of a sampling period, as shown in FIG. 6. Fourth, an ACof a first frequency is applied in every Ta of a sampling period and anAC of a second frequency is applied in every Tb of the sampling period,as shown in FIG. 7. Fifth, an AC of a first frequency is applied inevery Ta of a sampling period and an AC of a second frequency isconsistently applied irrespective of the Ta and Tb periods of thesampling period, as shown in FIG. 8.

In operation 930, intermediate signals for obtaining bio signals aresensed from the sensing unit 140. To detect the intermediate signals, aconnection among the electrodes shown in FIGS. 2 and 3 and its modifiedconnection can be used.

In operation 950, the first and the second bio signals are separatedfrom the intermediate signals detected in operation 930. To separate thefirst and the second bio signals, at least one of the temporalseparation and the electric separation can be used, as shown in FIGS. 2,3 and 6 through 8.

In operation 970, the items are analyzed by inputting the first and thesecond bio signals separated in operation 950, and data for each item isgenerated as the analysis results.

The exemplary embodiments of the present invention can be written ascomputer programs and can be implemented in general-use digitalcomputers that execute the programs using a computer-readable recordingmedium. Examples of the computer-readable recording medium includemagnetic storage media (e.g., ROM, floppy disks, hard disks, etc.),optical recording media (e.g., CD-ROMs, DVDs, etc.), and storage mediasuch as carrier waves (e.g., transmission through the internet). Thecomputer-readable recording medium can also be distributed over networkcoupled computer systems so that the computer-readable code is storedand executed in a distributed fashion. And the functional programs,codes and code segments for embodying the present invention may beeasily deducted by programmers in the art which the present inventionbelongs to.

As described above, according to exemplary embodiments of the presentinvention, since at least two bio signals having different physicalmechanisms can be measured, with at least one electrode in a sensingunit shared to apply the stimulus signal or to detect each bio signal, auser can easily and timely acquire the desired bio signals, and even ifmore bio signals have to be measured, the time required for measuringall the bio signals can be greatly reduced.

In addition, various kinds of bio signals can be simultaneously measuredwithout interference by using at least one of temporal separating andelectric separating, thereby being capable of integrating into onemeasurement apparatus. Therefore, cost reduction can be expected, and auser operation is simple.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

1. A bio signal measurement apparatus for simultaneously measuring afirst bio signal generated by a human body in response to a stimulussignal and a second bio signal naturally generated by the human body,the apparatus comprising: a stimulus signal generating unit which isconfigured to generate the stimulus signal to be applied to the humanbody; a sensing unit which is adapted to contact the human body andincludes a plurality of electrodes to which the stimulus signal isapplied, the plurality of electrodes detecting at least one intermediatesignal containing the first and second bio signals from the human bodythat occur simultaneously, and the sensing unit being configured toshare at least one of the plurality of electrodes to apply the stimulussignal to the human body and to detect the at least one intermediatesignal including the first bio signal and the second bio signal; asignal acquisition unit which is configured to acquire the detected atleast one intermediate signal and to separate the first bio signal andthe second bio signal from the at least one intermediate signal detectedfrom the sensing unit; a first temporal separating unit which isconfigured to operate in response to a control signal and to apply afirst stimulus signal in a first interval of each sampling period and asecond stimulus signal in a second interval of each sampling period, tothe human body via the sensing unit; a second temporal separating unitwhich is configured to operate in response to the control signal and toprovide a first intermediate signal detected by the sensing unit in thefirst interval and a second intermediate signal detected by the sensingunit in the second interval, to the signal acquisition unit; and whereinthe signal acquisition unit comprises: a first acquisition unit which isconfigured to obtain the first bio signal from a first intermediatesignal detected from the sensing unit; and a second acquisition unitwhich is configured to electrically separate and obtain the second biosignal from a second intermediate signal detected by the sensing unit,wherein the second acquisition unit comprises: a filtering unit which isconfigured to filter a frequency band in which the second bio signalexists from the second intermediate signal; and an isolating unit whichis configured to isolate the stimulus signal contained in the secondintermediate signal which is filtered.
 2. The apparatus of claim 1,wherein the isolating unit comprises one of a buffer, a photo couplerand a transformer.
 3. A bio signal measurement apparatus forsimultaneously measuring a first bio signal generated by a human body inresponse to a stimulus signal and a second bio signal naturallygenerated by the human body, the apparatus comprising: a stimulus signalgenerating unit which is configured to generate the stimulus signal tobe applied to the human body; a sensing unit which is adapted to contactthe human body and includes a plurality of electrodes to which thestimulus signal is applied, the plurality of electrodes detecting atleast one intermediate signal containing the first and second biosignals from the human body that occur simultaneously, and the sensingunit being configured to share at least one of the plurality ofelectrodes to apply the stimulus signal to the human body and to detectthe at least one intermediate signal including the first bio signal andthe second bio signal; and a signal acquisition unit which is configureto acquire the detected at least one intermediate signal and to separatethe first bio signal and the second bio signal from the at least oneintermediate signal detected from the sensing unit, the apparatusfurther comprising: a first temporal separating unit which is configuredto operate in response to a control signal and applies a first stimulussignal in a first interval of each sampling period and a second stimulussignal in a second interval of each sampling period, to the human bodyvia the sensing unit; a second temporal separating unit which isconfigured to operate in response to the control signal and provides afirst intermediate signal detected by the sensing unit in the firstinterval and a second intermediate signal detected by the sensing unitin the second interval, to the signal acquisition unit; and a controllerwhich is configured to generate the control signal, wherein the signalacquisition unit obtains the first bio signal from the first and secondintermediate signals and obtains the second bio signal by electricallyseparating the second intermediate signal.
 4. The apparatus of claim 3,wherein the signal acquisition unit: a filtering unit which isconfigured to filter a frequency band in which the second bio signalexists from the second intermediate signal; and an isolating unit whichis configured to isolate the second stimulus signal contained in thesecond intermediate signal which is filtered.
 5. The apparatus of claim4, wherein the isolating unit comprises one of a buffer, a photo couplerand a transformer.
 6. A bio signal measurement apparatus forsimultaneously measuring a first bio signal generated by a human body inresponse to a stimulus signal and a second bio signal naturallygenerated by the human body, the apparatus comprising: a stimulus signalgenerating unit which is configured to generate the stimulus signal tobe applied to the human body; a sensing unit which is adapted to contactthe human body and includes a plurality of electrodes to which thestimulus signal is applied, the plurality of electrodes detecting atleast one intermediate signal containing the first and second biosignals from the human body that occur simultaneously, and the sensingunit being configured to share at least one of the plurality ofelectrodes to apply the stimulus signal to the human body and to detectthe at least one intermediate signal including the first bio signal andthe second bio signal; and a signal acquisition unit which is configuredto acquire the detected at least one intermediate signal and separatesthe first bio signal and the second bio signal from the at least oneintermediate signal detected from the sensing unit, the apparatusfurther comprising: a first temporal separating unit which is configuredto operate in response to a control signal and to apply a first stimulussignal to the human body via the sensing unit in a first interval ofeach sampling period; a second temporal separating unit which isconfigured to operate in response to the control signal and to provide afirst intermediate signal detected by the sensing unit in the firstinterval and a second intermediate signal detected by the sensing unitin a second interval of each sampling period to the signal acquisitionunit; and a controller which is configured to generate the controlsignal, wherein a second stimulus signal is applied to the human bodyvia the sensing unit in the first and second intervals to detect a thirdintermediate signal from the sensing unit, and the signal acquisitionunit obtains the first bio signal from the first and third intermediatesignals and obtains the second bio signal by electrically separating thesecond intermediate signal.
 7. The apparatus of claim 6, wherein thesignal acquisition unit: a filtering unit which is configured to filtera frequency band in which the second bio signal exists from the secondintermediate signal; and an isolating unit which is configured toisolate the second stimulus signal contained in the second intermediatesignal which is filtered.
 8. The apparatus of claim 7, wherein theisolating unit comprises one of a buffer, a photo coupler and atransformer.
 9. A bio signal measurement apparatus for simultaneouslymeasuring a first bio signal generated by a human body in response to astimulus signal and a second bio signal naturally generated by the humanbody, the apparatus comprising: a stimulus signal generating unit whichis configured to generate the stimulus signal to be applied to the humanbody; a sensing unit which is adapted to contact the human body andincludes a plurality of electrodes to which the stimulus signal isapplied, the plurality of electrodes detecting at least one intermediatesignal containing the first and second bio signals from the human bodythat occur simultaneously, and the sensing unit being configured toshare at least one of the plurality of electrodes to apply the stimulussignal to the human body and to detect the at least one intermediatesignal including the first bio signal and the second bio signal; and asignal acquisition unit which is configured to acquire the detected atleast one intermediate signal and to separate the first bio signal andthe second bio signal from the at least one intermediate signal detectedfrom the sensing unit, the apparatus further comprising: a firsttemporal separating unit which is configured to operate in response to acontrol signal and applies first and second stimulus signals to thehuman body via the sensing unit in a first interval of a sampling periodof a pulse signal for detecting the at least one intermediate signal; asecond temporal separating unit which is configured to operate inresponse to the control signal and to provide a first intermediatesignal detected by the sensing unit in the first interval and a secondintermediate signal detected by the sensing unit in a second interval ofthe sampling period to the signal acquisition unit; and a controllerwhich is configured to generate the control signal, wherein the signalacquisition units obtains two first bio signals from the firstintermediate signal using first and second frequencies, respectively andobtains the second bio signal from the second intermediate signal. 10.The apparatus of claim 9, wherein the stimulus signal generating unitcomprises: a first current generator which is configured to generatecurrent of a first frequency to be used as the first stimulus signal; asecond current generator which is configured to generate current of asecond frequency to be used as the second stimulus signal; and acombining unit which is configured to combine the first and secondstimulus signals.
 11. The apparatus of claim 9, wherein the samplingperiod includes a third interval for discharging interposed between thefirst interval and the second interval.
 12. The apparatus of claim 11further comprising a resistor which is configured to externallydischarge the first and second stimulus signals remaining in the humanbody, in the third interval.
 13. A bio signal measurement method ofsimultaneously measuring a first bio signal generated by a human body inresponse to a stimulus signal and a second bio signal naturallygenerated in the human body, the method comprising: providing a sensingunit adapted to contact the human body, including a plurality ofelectrodes to which the stimulus signal is applied, the plurality ofelectrodes detecting at least one intermediate signal containing thefirst and second bio signals from the human body that occursimultaneously, and configured to share at least one of the plurality ofelectrodes to apply the stimulus signal to the human body and to detectthe at least one intermediate signal including the first bio signal andthe second bio signal; generating the stimulus signal to be applied tothe human body; and acquiring the detected at least one intermediatesignal and separating the first bio signal and the second bio signalfrom the at least one intermediate signal detected by the sensing unit,the method further comprising: applying a first stimulus signal in afirst interval of each sampling period and a second stimulus signal in asecond interval of each sampling period, to the human body, in responseto a control signal; and generating a first intermediate signal detectedby the sensing unit in the first interval and a second intermediatesignal detected by the sensing unit in the second interval, in responseto the control signal, wherein the first bio signal is obtained from thefirst and second intermediate signals and the second bio signal isobtained by electrically separating the second intermediate signal. 14.A bio signal measurement method of simultaneously measuring a first biosignal generated by a human body in response to a stimulus signal and asecond bio signal naturally generated in the human body, the methodcomprising: providing a sensing unit adapted to contact the human body,including a plurality of electrodes to which the stimulus signal isapplied, the plurality of electrodes detecting at least one intermediatesignal containing the first and second bio signals from the human bodythat occur simultaneously, and configured to share at least one of theplurality of electrodes to apply the stimulus signal to the human bodyand to detect the at least one intermediate signal including the firstbio signal and the second bio signal; generating the stimulus signal tobe applied to the human body; and acquiring the detected at least oneintermediate signal and separating the first bio signal and the secondbio signal from the at least one intermediate signal detected by thesensing unit, the method further comprising: applying a first stimulussignal to the human body via the sensing unit in a first interval ofeach sampling period, in response to a control signal; and providing afirst intermediate signal detected by the sensing unit in the firstinterval and a second intermediate signal detected by the sensing unitin a second interval of each sampling period, in response to the controlsignal, wherein a second stimulus signal is applied to the human bodyvia the sensing unit in the first and second intervals to detect a thirdintermediate signal from the sensing unit, and the first bio signal isobtained from the first and third intermediate signals and the secondbio signal is obtained by electrically separating the secondintermediate signal.
 15. A bio signal measurement method ofsimultaneously measuring a first bio signal generated by a human body inresponse to a stimulus signal and a second bio signal naturallygenerated in the human body, the method comprising: providing a sensingunit adapted to contact the human body, including a plurality ofelectrodes to which the stimulus signal is applied, the plurality ofelectrodes detecting at least one intermediate signal containing thefirst and second bio signals from the human body that occursimultaneously, and configured to share at least one of the plurality ofelectrodes to apply the stimulus signal to the human body and to detectthe at least one intermediate signal including the first bio signal andthe second bio signal; generating the stimulus signal to be applied tothe human body; and acquiring the detected at least one intermediatesignal and separating the first bio signal and the second bio signalfrom the at least one intermediate signal detected by the sensing unit,the method further comprising: applying a first and a second stimulussignal to the human body via the sensing unit in a first interval ofeach sampling period, in response to a control signal; and providing afirst intermediate signal detected by the sensing unit in the firstinterval and a second intermediate signal detected by the sensing unitin a second interval of each sampling period, in response to the controlsignal, wherein two first bio signals are obtained from the firstintermediate signal the using a first and a second frequency,respectively, and the second bio signal is obtained from the secondintermediate signal.
 16. The method of claim 15, wherein each samplingperiod includes a third interval for discharging between the firstinterval and the second interval.
 17. A non-transitory computer-readablerecording medium having recorded thereon a computer-readable program forperforming a bio signal measurement method of simultaneously measuring afirst bio signal generated by a human body in response to a stimulussignal and a second bio signal naturally generated by the human body,the method comprising: detecting at least one intermediate signalcontaining the first and second bio signals from the human body thatoccurs simultaneously, by using a sensing unit adapted to contact thehuman body, including a plurality of electrodes to which the stimulussignal is applied, the plurality of electrodes detecting the at leastone intermediate signal containing the first and second bio signals fromthe human body that occurs simultaneously, and configured to share atleast one of the plurality of electrodes to apply the stimulus signal tothe human body and to detect the at least one intermediate signalincluding the first bio signal and the second bio signal; generating thestimulus signal to be applied to the human body; and acquiring thedetected at least one intermediate signal and separating the first biosignal and the second bio signal from the at least one intermediatesignal detected by the sensing unit, wherein the acquiring andseparating the first and second bio signals comprises: applying a firststimulus signal in a first interval of each sampling period and a secondstimulus signal in a second interval of each sampling period to thehuman body via the sensing unit in response to a control signal;generating a first intermediate signal detected by the sensing unit inthe first interval and a second intermediate signal detected by thesensing unit in the second interval; obtaining the first bio signal fromthe first intermediate signal detected by the sensing unit; andelectrically separating and obtaining the second bio signal from thesecond intermediate signal detected by the sensing unit, wherein theelectrically separating and obtaining the second bio signal furthercomprises: filtering a frequency band in which the second bio signalexists from the second intermediate signal; and isolating the secondstimulus signal contained in the second intermediate signal which isfiltered.
 18. A non-transitory computer-readable recording medium havingrecorded thereon a computer-readable program for performing a bio signalmeasurement method of simultaneously measuring a first bio signalgenerated by a human body in response to a stimulus signal and a secondbio signal naturally generated by the human body, the method comprising:detecting at least one intermediate signal containing the first andsecond bio signals from the human body that occurs simultaneously, byusing a sensing unit adapted to contact the human body, including aplurality of electrodes to which the stimulus signal is applied, theplurality of electrodes detecting the at least one intermediate signalcontaining the first and second bio signals from the human body thatoccurs simultaneously, and configured to share at least one of theplurality of electrodes to apply the stimulus signal to the human bodyand to detect the at least one intermediate signal including the firstbio signal and the second bio signal; generating the stimulus signal tobe applied to the human body; and acquiring the detected at least oneintermediate signal and separating the first bio signal and the secondbio signal from the at least one intermediate signal detected by thesensing unit, wherein the method further comprises: applying a firststimulus signal in a first interval of each sampling period and a secondstimulus signal in a second interval of each sampling period, to thehuman body, in response to a control signal; and providing a firstintermediate signal detected by the sensing unit in the first intervaland a second intermediate signal detected by the sensing unit in thesecond interval, in response to the control signal, wherein the firstbio signal is obtained from the first and second intermediate signalsand the second bio signal is obtained by electrically separating thesecond intermediate signal.
 19. A non-transitory computer-readablerecording medium having recorded thereon a computer-readable program forperforming a bio signal measurement method of simultaneously measuring afirst bio signal generated by a human body in response to a stimulussignal and a second bio signal naturally generated by the human body,the method comprising: detecting at least one intermediate signalcontaining the first and second bio signals from the human body thatoccurs simultaneously, by using a sensing unit adapted to contact thehuman body, including a plurality of electrodes to which the stimulussignal is applied, the plurality of electrodes detecting the at leastone intermediate signal containing the first and second bio signals fromthe human body that occurs simultaneously, and configured to share atleast one of the plurality of electrodes to apply the stimulus signal tothe human body and to detect the at least one intermediate signalincluding the first bio signal and the second bio signal; generating thestimulus signal to be applied to the human body; and acquiring thedetected at least one intermediate signal and separating the first biosignal and the second bio signal from the at least one intermediatesignal detected by the sensing unit, wherein the method furthercomprises: applying a first stimulus signal to the human body via thesensing unit in a first interval of each sampling period, in response toa control signal; and providing a first intermediate signal detected bythe sensing unit in the first interval and a second intermediate signaldetected by the sensing unit in a second interval of each samplingperiod, in response to the control signal, wherein a second stimulussignal is applied to the human body via the sensing unit in the firstand second intervals to detect a third intermediate signal from thesensing unit, and the first bio signal is obtained from the first andthird intermediate signals and the second bio signal is obtained byelectrically separating the second intermediate signal.
 20. Anon-transitory computer-readable recording medium having recordedthereon a computer-readable program for performing a bio signalmeasurement method of simultaneously measuring a first bio signalgenerated by a human body in response to a stimulus signal and a secondbio signal naturally generated by the human body, the method comprising:detecting at least one intermediate signal containing the first andsecond bio signals from the human body that occurs simultaneously, byusing a sensing unit adapted to contact the human body, including aplurality of electrodes to which the stimulus signal is applied, theplurality of electrodes detecting the at least one intermediate signalcontaining the first and second bio signals from the human body thatoccurs simultaneously, and configured to share at least one of theplurality of electrodes to apply the stimulus signal to the human bodyand to detect the at least one intermediate signal including the firstbio signal and the second bio signal; generating the stimulus signal tobe applied to the human body; and acquiring the detected at least oneintermediate signal and separating the first bio signal and the secondbio signal from the at least one intermediate signal detected by thesensing unit, wherein the method further comprises: applying a first anda second stimulus signal to the human body via the sensing unit in afirst interval of each sampling period, in response to a control signal;and providing a first intermediate signal detected by the sensing unitin the first interval and a second intermediate signal detected by thesensing unit in a second interval of each sampling period, in responseto the control signal, wherein two first bio signals are obtained fromthe first intermediate signal using a first and a second frequency,respectively, and the second bio signal is obtained from the secondintermediate signal.